The present invention relates to a display device having a multiple gradation display mode and a small gradation display mode (the number of gradations is smaller than that of the multiple gradation display mode) and a driving method thereof and more particularly to a display device such as a liquid crystal display, an organic electroluminescence (EL) display, a plasma display and a field-emission display and a driving method thereof. Furthermore, the present invention relates to a display device having reduced power consumption in partial display.
U.S. Patent Application Serial No. 2005/0179677 (JP-A-2005-234029) discloses an image display device including a scanning circuit composed of a shift register for transferring data in synchronism with a horizontal synchronizing signal Hsync and an AND circuit for producing an output signal on the basis of an enable signal and an output signal of the shift register in order to select a non-display area in the partial display by a plurality of lines to write a signal. A high-level (Hi) period of a start signal supplied to the shift register is set to a plurality of horizontal periods, for example, 4 horizontal periods and the enable signal is made to be high level during only one horizontal period in the plurality of horizontal periods, for example, 4 horizontal periods, so that the scanning circuit capable of selecting a plurality of lines (4 horizontal lines) simultaneously can be realized.
U.S. Pat. No. 6,781,605 (JP-A-2002-366115) discloses a display device in which a current flowing through a circuit part (ladder resistors) for producing gradation voltages unnecessary for display among circuits for producing a plurality of gradation voltages is reduced when the number of gradations to be displayed is reduced.
Further, in display devices for cellular phones, the power consumption in the partial display is not reduced and it is difficult to realize the partial display mode.
U.S. Pat. No. 7,123,247 (JP-A-2006-3923) discloses a display device in which a partial display area is scanned to be driven every frame period and other display area except the partial display area is scanned to be driven every odd frame period to thereby reduce the power consumption.